2.2 Measuring Earthquakes

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Vocabulary

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focus - where rocks beneath surface breaks;triggers earthquakes
epicenter - surface directly above focus
seismic waves - vibrations from earthquake
p waves - earthquake waves that act like accordian
s waves - earthquake waves that vibrates side to side and up and down
surface waves - slower than p and s waves, more severe ground movements
magnitude - measurement of earthquake waves
Mercalli scale - measurement of earthquake waves
Richter scale - rates size of seismic waves
moment magnitude scale - estimates total energy from earthquake

Outline

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Seismic Waves

• primary waves
  • "P" waves
  • first to arrive
• Secondary waves
  • "S" waves
  • after p waves
• Surface waves
  • more powerful than p and s waves

Detecting Seismic Waves

• electronic seismographs

Measuring Earthquakes

• Magnitude
• Mercalli scale
• Richter Scale
• Moment magnitude scale

Locating the Epicenter

• seismic waves
• p and s waves

Diagram

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